In recent years, agricultural implements have employed forced air conveyance systems to deliver seed, fertilizer and herbicides. As the size of these agricultural implements continues to grow, the versatility of such implements becomes more significant. In particular, large air carts or air seeders have become increasingly popular for conveying seed, fertilizer and other product without strict regard for the exact placement of the product. Typically, these large air carts are used for dry land farming (e.g., cereal crops, etc.).
For certain crop planting applications that require row crop planting or seed singulation (e.g., corn, soybean, etc.), the air cart can be combined with an inductor assembly adapted to feed seed or other product from a larger storage hopper into smaller reservoirs located at on-row planting units, also referred to as singulators or receivers. The combined air cart and inductor assembly enables a farmer to singulate planting of seeds on-row from one central hopper filling location. Thereby, the nurse inductor assembly and air cart allows a farmer to plant more acreage before having to stop to fill the central hopper again, resulting in quicker planting and less labor while maintaining the precision spacing available by on-row singulation.
U.S. Pat. No. 6,253,693 discloses a nurse inductor assembly in flow communication with a storage hopper of seed mounted on an air cart. The air cart includes a fan to provide a forced air stream through the inductor assembly. The forced air stream is directed by the inductor assembly to a general location of a seed mass delivered from the storage hopper. The forced air stream engages the seed mass, entraining the seed into the air stream. A movable seed control gate is configured to regulate an angle of repose of a surface of the seed mass, which affects the entrainment of the seed into the forced air stream. The inductor assembly conveys the combined stream of forced air and seed through a series of inductor sections that each leads to an isolated inductor distribution tube and ultimately to a distribution line leading to associated series of remote receivers for application of the seed in an agricultural field. When the receiver is full of seed, the air stream is restricted from escaping the receiver and ultimately reduces the capacity of the air stream at the inductor assembly to induce the seed into the inductor distribution tubes.
This nurse inductor assembly has several drawbacks. For example, the velocity of the combined stream of air and seed product through the distribution line slows as the stream encounters the increased resistance associated with traveling through the deposited seed product at the receiver. If allowed to be induced into the distribution lines below the minimum carrying velocity, the seed product causes blocking of the seed distribution lines. Any seed product that had been entrained into the slower flowing air stream drops out under the force of gravity. A certain quantity of dropped seed product will deposit toward low points in the distribution lines, increasing plugging opportunities. Another drawback of this nurse inductor assembly is that the movable gate is difficult to adjust for various products of different sizes and properties, which can cause uneven product flow to the receivers and/or plugging opportunities in the inductor assembly or distribution lines. Also, the interference of the seed control gate to the flow of the combined stream of air and seed will cause the seed to bridge across the inductor chamber of the inductor apparatus and inhibit the entrainment of seed into the forced air stream.
U.S. Pat. No. 7,222,029 to Johnson et al., and assigned to CNH America, LLC, the assignee of the present application, and the disclosure of which is incorporated herein by reference, describes an inductor assembly for a product conveyance system that overcomes many of the drawbacks of prior art inductor assemblies or “inductor boxes” such as that described in the '693 patent. More particularly, the patent to Johnson et al. describes an inductor assembly for forced air conveyance of product that provides sufficient carrying capacity to convey seed through a distribution line to a remotely located receiver.
Notwithstanding the benefits provided an inductor assembly such as that described by Johnson et al., there remains a need for uniformity of the combined stream of air and product across the inductor assembly and into the distribution lines. That is, many inductor assemblies contain a series of inductor segments, with each inductor segment generally comprised of an upper conduit and a lower conduit. Each conduit has a respective inlet and a respective outlet, and each inlet is designed to receive a combined product and forced air stream that is passed through its corresponding outlet. In a typical configuration, the length of the conduits is not uniform, which can result in a pressure differential across the profile of the inductor segments. In general, the flow rate through the shorter conduits is greater than the flow rate through the longer conduits. As a result, more product may be conveyed through some distribution lines than conveyed through others, which can ultimately lead to an uneven distribution of product to the individual on-row units.